This invention relates to a wafer-type swing check valve used to control the backflow of fluids in a pipeline. Wafer-type check valves of this general type have previously been used to control backflow, but these valves have several disadvantages. Fabrication of present swing check valves often involves extensive machining and substantial time for hand assembly. Frequently the valve components are misaligned during assembly causing a malfunction of the hinged disc which usually can not be detected until the valve is in service.
In certain valves, the smoothness of the hinge swing may be impaired if the bearing portion of the pin is not properly aligned. In other valves, the components can rotate during operation causing valve malfunction. Repair or replacement of the disc is often difficult and timeconsuming requiring complete removal of the check valve from the line. In valves of this general type, the orifice in the check valve usually creates a substantial restriction to full-flow and in many of these valves the diameter of the hinged disc is substantially smaller than the diameter of the piping connected to the check valve. In still other check valves with hinged disc diameters approaching the diameter of the connected piping, the hinged disc is restricted to open substantially less than 90.degree..
In many present valves, back-flow leakage through the valve occurs due to improper seating of the disc, especially where the disc seat is non-tapered or where the disc must slide over support slots, and, it has been necessary to remove the entire valve from the line whenever the seat is relapped, the orifice in the check valve was to be changed, or, the disc opening pressure was to be modified. Moreover, relapping of the seat often affects the alignment of the hinge relative to the valve seat. Present valves utilize a seat which is integral with the body wherein wear or damage to the seat often necessitates replacement of the valve body.
An object of the present invention is to produce a large orifice wafer-type swing check valve having a disc and disc support which can be assembled and checked for proper operation prior to being inserted into the valve body and line.
An additional object is to produce a positive closing check valve in which the size of the disc and the disc opening pressure can be quickly and easily altered without removing the entire check valve from the line.
Another object is to provide low cost check valve in which the seat can be easily lapped or relapped for improved sealing without affecting hinge alignment.
A further object of this invention is to provide a non-rotatable tapered seat which can be easily and positively seated in the valve body by a low back pressure.
The wafer-type swing check valve which is the subject of this invention includes a tubular body which may have threaded or flanged connections for positioning and hydraulically sealing the valve in the fluid flow line. The inlet or outlet connections may be counter-bored and machined to receive a machined and lapped disc support. In the preferred embodiment, the valve connections are flanged and the inlet flange has been counterbored to receive the disc suppport. The disc support has a tapered seat surrounding a passage therethrough adapted to engage a disc, and has hinge lugs to permit swinging movement of the disc about the hinge pin centerline. The tubular body has an integrally cast, outwardly extending protrusion defining a recess therein complementary to an extended portion of the disc on which a hinge lug is located. The location of the hinge in the recess permits the disc to open 90.degree..
The disc support seat may be made removable from the disc support to facilitate relapping or replacement of the disc support seat. A wire hinge may optionally be used in the hinge means to correct for misalignment between the seat and the hinge pin; to dampen vibration transmitted by the disc to the pin; and, to permit the use of a circular, easily machined disc.